1. Field of the Invention
The present invention relates to a driving apparatus for a multiplex-winding rotary machine, which is capable of continuing to drive the rotary machine even if rotational position detection means has failed.
2. Description of the Background Art
A driving apparatus for a rotary machine, in order to drive the rotary machine in a desired state, detects the position of a rotor of the rotary machine by a rotational position detector to perform control to generate a voltage instruction for voltage application to the rotary machine, and applies, to the rotary machine, voltage based on the voltage instruction by voltage application means, thereby driving the rotary machine.
The rotational position detector, current detection means, the voltage application means, a rotary machine winding, and the like composing the rotary machine driving apparatus can sometimes fail, and accordingly, various methods are proposed for continuing to drive the rotary machine even when failure occurs.
Patent Document 1 discloses that, in a rotary machine control apparatus for controlling a rotary machine having a rotor and a stator facing the rotor, a sensor failure determination section determines whether or not a resolver has failed. In normal state in which the resolver does not fail, the rotary machine is controlled by using a detection rotation angle detected by the resolver. If the resolver has failed, the rotary machine is controlled by using an estimation rotation angle obtained by a rotation angle estimation section.
Patent Document 2 discloses that, in a multiphase rotary machine having a plurality of winding groups each including windings for a plurality of phases, a plurality of inverter sections each having switching means corresponding to each phase of windings are provided for the respective winding groups. When OFF-failure occurs in which conduction of the switching means is not allowed, in the failed inverter section which includes the switching means that has failed, the switching means other than the switching means that has failed in the failed inverter section is controlled based on a failure phase current instruction value calculated as a function about the rotational position of the multiphase rotary machine and a torque instruction or a function about the rotational position and a q-axis current instruction value, and a normal inverter section other than the failed inverter section is controlled in the same manner as in normal state.
Patent Document 3 discloses that, in a multiphase rotary machine having a plurality of winding groups each including windings corresponding to a plurality of phases, inverter sections of a plurality of systems, each having a leg composed of a high-potential-side switching device and a low-potential-side switching device corresponding to each phase of the multiphase rotary machine, are provided for the respective winding groups. When short-circuit failure occurs in which the switching device keeps conductive state regardless of control to turn off the switching device, all the switching devices in the failed system are controlled to be OFF while the multiphase rotary machine continues to be driven by the leg in the system that does not fail, and the switching devices in the system that does not fail are controlled so as to cancel the output that is caused along with the short-circuit failure in the failed system and that operates against the drive of the multiphase rotary machine, or so as to reduce the influence of the output on the driving.
Patent Document 4 discloses an electric power steering apparatus which assists steering force of a driver by using driving force for a rotary machine, the electric power steering apparatus including: control means which sets a current instruction value needed for the driving force of the rotary machine; a plurality of power converters; a plurality of groups of windings, corresponding to the plurality of power converters, which generate the driving force of the rotary machine by being respectively supplied with current from the plurality of power converters; and failure detection means which detects failure of the power converter or the winding. When the failure detection means has detected failure, the current instruction value is reduced from that in normal state, and current is continuously supplied from the normal one of the power converters to the corresponding windings.
Patent Document 1: Japanese Laid-Open Patent Publication No. 2010-29031
Patent Document 2: Japanese Laid-Open Patent Publication No. 2011-78221
Patent Document 3: Japanese Laid-Open Patent Publication No. 2011-78230
Patent Document 4: Japanese Laid-Open Patent Publication No. 2011-131860
Patent Document 1 proposes a method for continuing to drive a rotary machine when a resolver has failed in the rotary machine. However, there is a problem that if rotational position detection means has failed in a multiplex-winding rotary machine, the rotation performance is decreased.
In Patent Documents 2 to 4, a multiplex-winding rotary machine having a plurality of winding groups each including windings for a plurality of phases, and a plurality of voltage application means for the respective winding groups, are provided, whereby, even if some of the rotary machine windings or the voltage application means have failed, the rotary machine can continue to be driven by the other normal rotary machine windings and voltage application means. However, there is a problem that if rotational position detection means has failed, it is impossible to appropriately cope with the failure.